Genetic Relatedness and Chemical Profiles in an Unusually Peaceful Eusocial Bee

Abstract

Colonies of the stingless bee Tetragonilla collina frequently occur in unusually high densities and in direct neighborhood (nest aggregations), in rainforests of Southeast Asia. To investigate whether close relatedness and/or similar chemical profiles facilitate the co-occurrence of multiple T. collina colonies, we investigated aggressive behavior, genetic relatedness and cuticular hydrocarbon (CHC) profiles within and between colonies and nest aggregations. Although 17 out of 19 colonies within aggregations were largely unrelated, intraspecific aggression between different colonies was basically absent both within and among aggregations. This lack of aggression should favor social parasitism and hence the occurrence of unrelated individuals within a colony. However, low within-colony relatedness was found in only five out of 19 colonies where it may be explained by queen turnover or the occurrence of foreign workers. CHC profiles of colonies within and among aggregations were statistically different. However, many workers could chemically not be assigned to their maternal colony, indicating considerable overlap among colonies in odor profiles of workers. Moreover, odor profiles tended to be more similar within than among aggregations, although most colonies were unrelated. Thus, CHC profiles were a poor indicator of relatedness in T. collina. The lack of correlation between relatedness and chemical similarity in T. collina may be explained by the incorporation of resin-derived terpenes in their CHC profiles. The composition of these terpenes was highly similar among colonies, particularly within aggregations, hence potentially decreasing chemical distinctiveness and increasing behavioral tolerance.

Context affects nestmate recognition errors in honey bees and stingless bees

“…The importance of context may even help explain unusual data, especially negative results. In a study in Tetragonilla collina, a discriminator bee was transferred from her colony into a clean Petri dish and presented with a dead bee from her colony, another colony within the same aggregation, or from a foreign aggregation (Leonhardt et al, 2011). The discriminator displayed almost a complete lack of aggression and earned the title 'unusually peaceful bee'.…”

Resin Use by Stingless Bees: A Review

“…Resin-derived terpenes present in the cuticle might also help facilitate nest aggregations. These compounds may mask chemical differences between bee species, contributing to reduced interspecific aggression [105]. One study compared aggressive behaviors between bees from the same nest aggregation, different aggregations, and nonaggregated nests, and found that aggression was reduced between bees from associated colonies [100].…”

Cryptic castes, social context and colony defence in a social bee, Tetragonula carbonaria

“…Given the cost of these antagonistic encounters, there is a strong functional benefit to ensuring that defensive behaviour is context‐specific. Our results may help explain the surprisingly low levels of aggression towards non‐nestmates in other bees, revealed from trials in isolated arenas (Dew, Gardner & Schwarz, ; Leonhardt, Form, Blüthgen, Schmitt & Feldhaar, ) but see (Breed & Page, ). Social context is also important in honey bees, whose defensive behaviour is usually only expressed at the nest entrance and environmental or social cues may be required to discriminate nestmates (Buchwald & Breed, ; Downs & Ratnieks, ).…”

“…N = 10. [Colour figure can be viewed at wileyonlinelibrary.com] Schwarz, 2014;Leonhardt, Form, Blüthgen, Schmitt & Feldhaar, 2011) but see (Breed & Page, 1991). Social context is also important in honey bees, whose defensive behaviour is usually only expressed at the nest entrance and environmental or social cues may be required to discriminate nestmates (Buchwald & Breed, 2005;Downs & Ratnieks, 1999).…”